CTOP is a tool which allows you to quickly find out what's happening on a machine running Cassandra. It is particularly useful on a cluster with multiple-tenants, multiple-applications, and large numbers of tables. If you suspect that the performance is not good, then you can use this to figure out which table is giving you trouble.
Allow CTOP some time to collect metrics, then press SPACE to refresh the display. You will see your tables listed by Reads/s (in descending order).
You can press SPACE at any time to refresh the display
The numbers 1 through 5 change the sorting order:
1: Order by Reads/s
2: Order by Writes/s
3: Order by the amount of disk-space used (in Bytes)
4: Order by read-latency (in miliseconds)
5: Order by write-latency (in miliseconds)
Pressing "Q" will quit
Metrics are for one node only (not cluster-wide)
Notes
CTOP should run on anything. Originally was developed on Ubuntu, and
it's reported to run on CentOS and MacOS X.
Pre-requisites:
CTOP uses "libmx4j-java" (an HTTP -> JMX) to retrieve JMX metrics from Cassandra (there was no easy way to query JMX directly), so this needs to be in the class-path where Cassandra can find it upon startup (with Ubuntu it is enough to do "apt-get install libmx4j-java", then to re-start Cassandra).
Cassandra needs to be told how to run MX4J (the default is to listen to the interface that Cassandra listens on):